Source of groundwater contamination near South Tahoe’s ‘Y’ remains a mystery
SOUTH LAKE TAHOE — An investigation into contaminated groundwater near South Lake Tahoe’s “Y” intersection has been unable to determine the source of a potentially harmful solvent discovered in the area in 2014.
In a report released this week, URS Corporation Americas reported five of 42 water samples taken in a nine-block area of the South Shore showed concentrations of tetrachloroethylene, or PCE, at levels less than what is legally allowed in drinking water by the U.S. Environmental Protection Agency. The remaining samples contained PCE in concentrations less than the reporting limit for public drinking water systems, according to the report. The site investigated by URS is bounded by 11th Street to the northwest, Roger Avenue to the south-southwest, Patricia Lane to the northeast and 5th Street to the southeast.
“We expected to find widespread PCE all over that area, and we didn’t,” said Lisa Dernbach, a senior engineering geologist for the Lahontan Regional Water Quality Control Board.
PCE is normally associated with dry cleaning, but can also be used for metal degreasing and is an ingredient in paint strippers. The compound is classified as a probable carcinogen that has the potential to increase the risk of cancer after consumption over many years, potentially depress the central nervous system and increase the risk of Parkinson’s disease, according to a statement from the Lahontan Water Board.
Businesses that use or may have used PCE have been researched by Lahontan. In its report, URS recommended additional sampling to further investigate possible sources of PCE. It’s possible the PCE contaminating wells in the area is deeper in the ground than what was sampled during the URS investigation, Dernbach said. The Water Board expects to request funding for additional testing from the California State Water Resources Board, although that funding is still subject to approval.
The two municipal wells where PCE contamination was discovered in 2014 are located within the Lukins Brothers Water Company. Both wells have been offline since July 2014. The water company is working with the state on funding the construction of a granulated activated carbon system to treat contamination in the wells, said Lukins spokeswoman Jennifer Lukins in an email. The system would be very similar to a plant installed in the Tahoe Keys, she added.
“Pending the release of State funding, we hope to have the system constructed during 2016 and in operation as soon as we have met all testing requirements from the Department of Water Resources,” Lukins said.
How the treatment plant could impact rates for Lukins customers isn’t known and will depend on what grants and loans are used to pay for the treatment facility.
“We, of course, aim to minimize the burden to the customers as much as possible,” Lukins said.
The water company will remain connected to South Tahoe Public Utility District to provide supplemental water supply, Lukins added.
The Lahontan Water Board will hold a public meeting to help people understand the URS report from 10 a.m. to 12 p.m. Friday, Feb. 5, at the Water Board’s annex office at 971 Silver Dollar Ave. in South Lake Tahoe. During the meeting URS will describe how the investigation was conducted and present its findings.
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